Heat exchange equipment



Nov. 28, 1939;. J. M. JENKINS 'HEAT EXCHANGE EQUIPMENT Filed March 19, 1938 l'atented Nov. 28, 1939 UNITED STATESA 2,181,486 HEAT EXCHANGE EQUrPMEN-i- Janies M. Jenkins, Philadelphia, Pa., assignor to Andale Company, Philadelphia, Pa., a corporation of Pennsylvania Application March 19, 1938, Serial No. 196,865

2 Claims. (Cl. 257-224) 'I'his invention relates to heat exchange equipment and especially to a heat exchange unit o f the tube and shell type.

The invention is more particularly concerned 5 with a tube sheet arrangement in which two tube sheets are employed adjacent anend of the tube bundle, the two tube sheets being secured to each other and providing a venting space therebetween.

According to the invention, provision is made for exposing to the shell space a substantial area not only of the inner tube sheet but also of the outer tube sheet, this being of importance for reasons pointed out more fully hereinafter, although at this time it is noted that the arrangement is of substantial advantage in reducing leakage around the tubes, especially at the inner tube sheet, as has occurred at times in various installa tions, particularly Where very high temperatures are encountered.

How the foregoing objects and advantages are attained will appear more fully in the following v description making reference to the accompany- -ing drawing illustrating a preferred embodiment of the invention.

In the drawing, a heat exchanger shell is designated'by the numeral l,this shell'conveniently being of cylindrical shape and having inlet and outlet connections 2 and 3 adjacent opposite ends thereof. A tube nest incorporating a plurality of tubes i extends lengthwise through :the shell, and

at the two ends of the tube nest-li preferably provide inner tube sheets 5 and 6 and outer tube sheets l and 8. The outer tube sheet 8 at one end of the unit (the upper end in the drawing) carries a header 9 secured thereto as by studs I0, this header serving as the inlet headerand having an inlet connection Ii. Corresponding outlet header parts l2, I3 and it are carried by the outer sheet l at the other end of the unit.

The shell, tubes, headers and connections thus provide for counteriiow of two uids in heat exchange relation, one through the shell Iand the other through the tubes, the shell space, if desired, being baiiled as by means of plates l5 arranged in'any convenientmanner to provide a sinuous path through the shell. A

At one end of the unit (the lower end in the drawing) the outer tube sheet 1 is of larger diameter than the shell and is bolted to a securing ring I6 as at Il. The inner sheet 5 at this end is of substantially smaller diameter than the inside diameter of the shell and is provided with a peripheral ridge I8 seated against the inner face of the outer sheet, the two sheets preferably being welded together by a joint I9. This arrangement provides for securing the sheets together in spaced relation to provide an intersheet space 2U having a vent passage 2| to the exterior of the unit through the outer sheet 1.

i. At the other end of the unit the outer sheet 8 5 is preferably of such diameter as to fit into the shell in order to permit freedom for relative ex-A pension and contraction of the tubes and shell.l A flexible bellows joint 22 is secured at one edge 23 to the shell and. at its other edge to a ring 2d 10 which may be bolted to the outer face of the outer sheet 8 as by studs 25.

The inner sheet 6 at this end is arranged in a manner similar to that described in connection with sheet 5, i. e. is provided with a peripheral 15 rib 26 welded to the sheet 8 at 2l, the sheet 9 also being provided with a vent passage 28 communicating with the inter-sheet space.

Inconsidering the operation and advantages of the structure described, attention is rst di- 20 rected to the fact that the multiple tube sheet arrangement provides a number of important advantages mentioned herebelow, although it is pointed out that the employment of two tube sheets broadly is not a part of the present in- 25 vention per se. The advantages in question include provision for venting of any leakage which may occur around the tubes through either of the tube sheets, thus, either from, the shell space or from the header space, 'I'he two sheets vented 30 in this manner also prevent intermingling of the two iiuids, as would result upon leakage around the tubes in a unit employing only a single tube sheet. Still further, the double tube sheet arrangement makes possible introducing air or other 35 iiuid under pressure into the inter-sheet space for the purpose of testing thetube joints in both sheets. If desired, the vent passages for the inter-sheet. spaces may be threaded at their outer ends for coupling with piping for the purpose 40 of carrying away any leakage, to a point remote from ,the equipment or exteriorly of the'building in which it is housed.

The present invention attains not only these advantagesv but further overcomes certain disad- 45 vantages encountered in prior units employing double tube sheets.

The point in question may be considered to best advantage when bearing in mind that umts of this type are frequently employed, for instance 50 in chemical industries, in situations Where one or the other or both of the fluids are at very high temperature. In certain prior arrangements the 'high temperatures have resulted in irregular expansion and contraction of the two sheets with 55 preventing leakage.

consequent non-uniform stresses as between the two sheets. irregularity of heating of the two tube sheets has resulted from arrangement or disposition of the sheets in such manner that only one of them is exposed to the shell space, or that the outer one is subject tol substantial cooling, or both.

To overcome these difficulties, the present invention provides for substantial exposure of both of the tube sheets to the shell space. This is eff fected by securing or joining the outer of the two sheets to the shell and by making the inner sheet of a diameter considerably less than the inside diameter of the shell, whereby to expose a substa'ntial annular area of the inner face of the outer sheet to the shell space. In consequence,l

. contact of the uid in the shell space eectively heats both of the tube sheets, the heat in the outer sheet being readily transmitted by con.

since it provides for approximately uniform stresses in the two tube sheets, the tube joints in the sheets in consequence remaining tight and This is accomplished moreover without sacrificing any of the important advantages of the double tube sheet arrangement.

I claim:

1. In a tube and shell heat exchanger, a tube\ change tubes eachextended through the venting space and each having a uid tight joint in each of said sheets, the two sheets being in engagement with each other substantially only in a narrow zone surrounding said venting space, the first tube sheet having a substantial area of its inner face exposed to the shell space, and means for Venting said venting space.

2. In a tube and shell heat exchanger, a tube sheet at an end of the shell, a second tube sheet of smaller diameter positioned at the inner face of the iirst sheet with a venting space therebetween, a nest of heat exchange tubes each extended through said venting space and each having a fluid tight joint in each of said sheets, the venting space being peripherally closed adjacent the edge of the tube sheet of smaller diameter, and the rst tube sheet being joined to the shell radially outwardly of the edge of the second tube sheet to provide for exposure of a substantial area of the inner face of the first tube sheet to the shell space, and means `for venting the venting space exteriorly of the spaces in communi cation' with the shell and tubes..

JAIVIES M.' JENHNS. 

